The person who asked this question at #digpres14 was specifically asking about external storage media used for transfer rather than, say, external storage media in manuscript collections that are possibly collection items themselves.

1 - In our work at Rhizome, we often get material from artists on a CD-ROM or similar media. We ingest the files on the disk and throw it away. However, it is often the case that the files do not work without something we missed from the disk. I wish that we had kept the actual CDs from ten years ago to be able to access these artworks.

2 - Similar to the RFP for packet-switching with pigeons, sometimes it is faster to transfer a physical harddrive than to send over network. In this case, the hard drive is simply a really, really big packet.

3 - At Portico we keep everything. Even for a zip file taken over FTP, we maintain the ZIP file. This is because even as a logical container, we have to reverse-engineer from the ZIP to whatever should be inside. To be cautious with the contents of these files, we maintain the ZIP.

4 - Don't ever try to get the IT department to keep these materials, they don't want them!